1. Field of the Invention
The invention relates to a light-emitting structure. Particularly, the invention relates to a semiconductor light-emitting structure.
2. Description of Related Art
Along with development of photoelectric technology, fabrication and application of light-emitting diodes (LEDs) have gradually become mature. Since the LED has advantages of low pollution, low power consumption, short response time, long service life, etc., it has been widely used in various light source or illumination domains, and has replaced conventional light-emitting devices such as fluorescent tubes, incandescent bulbs or halogen lamps. Along with the world gradually rising environmental protection awareness, the LED is expected to become a major illumination light source in the future to replace the current fluorescent tubes.
A main structure of the LED (a LED chip) includes an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer. Moreover, in order to connect the LED chip to an external circuit, electrodes are respectively disposed on the N-type semiconductor layer and the P-type semiconductor layer, and the electrodes are, for example, electrodes containing gold. The electrode can be electrically connected to an external circuit through wire bonding or flip-chip bonding. Moreover, a part of the surface of the conventional LED chip is covered by an insulating layer to avoid a short circuit phenomenon when the chip is polluted.
However, generally, a top surface or a side surface of the electrode of the LED chip is not covered by the insulating layer, or even if a part of the top surface or the side surface of the electrode is covered by the insulating layer when the electrode is originally manufactured, due to a poor adhesion between the insulating layer and the top surface or the side surface of the electrode, after a long time utilization, a part of the insulating layer covering the electrode may fall off. Therefore, water vapor is easy to invade the electrode. Generally, the bottom of the electrode has a metal adhesive layer suitable for adhering a semiconductor layer. When the metal adhesive layer encounters the water vapor or a reverse voltage, it is liable to dissociate and migrate to external of the electrode, so that the metal adhesive layer is gradually disappeared, which may result in a fact that the electrode falls off from the semiconductor layer. Therefore, a service life of the LED chip is hard to be prolonged due to falling off of the electrode.